1. Field of the Invention
The invention relates to depositing a coating solution and an ophthalmic wafer into an open mold prior to injection molding an optical lens on top of the wafer to produce a functionally enhanced coated lens.
2. The Prior Art
In-situ coating via a direct injection process, so called in-mold coating was originally developed to improve the surface appearance of sheet molding compound (SMC) parts molded by compression molding. Recent years it's been applied to injection molded thermoplastic parts as it is described in the following patent and patent application: U.S. Pat. No. 6,180,043, U.S. Pat. No. 6,676,877, US 2003-0077425, US 2003-0082344, or US 2003-0099809)
For the regular injection molding process, the thermoplastic piece is ejected out of the mold once it is rigid enough to resist the deformation caused by ejection. For in-situ coating injection, it integrates with injection molding via injecting thermoset coating liquid on the exterior surface of the thermoplastic piece when the thermoplastic piece is solidified to the degree that it won't be damaged by the coating injection. More coating is injected after the desired surface coverage is obtained to achieve certain coating thickness. The coating thermally cures by the residual heat from the thermoplastic piece and the continuously heated mold.
U.S. Published Patent Application 2004/0125335 discloses a film insert molding technique where the film is coated prior to placement in the injection molding cavity. The coating consists of an epoxy functional silane dissolved in aqueous-organic solvent mixtures. The coating is applied to the film by conventional dip coating, spray coating, spin coating, etc. The coating must be pre-cured by driving off the solvent which creates VOCs. The pre-cure step must be carried out separate and independent from the mold, as the VOCs would otherwise collect in the mold cavity and adversely effect the injection molding process.
No successful application of in-situ coating via direct injection has been found on ophthalmic lens. The major challenges on this application are: development of optical quality coating system suitable for this technology, achievement of desirable coating thickness and its uniformity, process control on thermoplastic injection and the integrated coating injection.